/* * Adapted from Open Shading Language with this license: * * Copyright (c) 2009-2010 Sony Pictures Imageworks Inc., et al. * All Rights Reserved. * * Modifications Copyright 2011, Blender Foundation. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of Sony Pictures Imageworks nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include #include #include "osl_closures.h" #include "util_math.h" CCL_NAMESPACE_BEGIN using namespace OSL; // anisotropic ward - leaks energy at grazing angles // see http://www.graphics.cornell.edu/~bjw/wardnotes.pdf class WardClosure : public BSDFClosure { public: Vec3 m_N; Vec3 m_T; float m_ax, m_ay; WardClosure() : BSDFClosure(Labels::GLOSSY) { } void setup() { m_ax = clamp(m_ax, 1e-5f, 1.0f); m_ay = clamp(m_ay, 1e-5f, 1.0f); } bool mergeable (const ClosurePrimitive *other) const { const WardClosure *comp = (const WardClosure *)other; return m_N == comp->m_N && m_T == comp->m_T && m_ax == comp->m_ax && m_ay == comp->m_ay && BSDFClosure::mergeable(other); } size_t memsize () const { return sizeof(*this); } const char *name () const { return "ward"; } void print_on (std::ostream &out) const { out << name() << " (("; out << m_N[0] << ", " << m_N[1] << ", " << m_N[2] << "), ("; out << m_T[0] << ", " << m_T[1] << ", " << m_T[2] << "), "; out << m_ax << ", " << m_ay << ")"; } float albedo (const Vec3 &omega_out) const { return 1.0f; } Color3 eval_reflect (const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const { float cosNO = m_N.dot(omega_out); float cosNI = m_N.dot(omega_in); if (cosNI > 0 && cosNO > 0) { // get half vector and get x,y basis on the surface for anisotropy Vec3 H = omega_in + omega_out; H.normalize(); // normalize needed for pdf Vec3 X, Y; make_orthonormals(m_N, m_T, X, Y); // eq. 4 float dotx = H.dot(X) / m_ax; float doty = H.dot(Y) / m_ay; float dotn = H.dot(m_N); float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn); float denom = (4 * (float) M_PI * m_ax * m_ay * sqrtf(cosNO * cosNI)); float exp_val = expf(-exp_arg); float out = cosNI * exp_val / denom; float oh = H.dot(omega_out); denom = 4 * (float) M_PI * m_ax * m_ay * oh * dotn * dotn * dotn; pdf = exp_val / denom; return Color3 (out, out, out); } return Color3 (0, 0, 0); } Color3 eval_transmit (const Vec3 &omega_out, const Vec3 &omega_in, float& pdf) const { return Color3 (0, 0, 0); } ustring sample (const Vec3 &Ng, const Vec3 &omega_out, const Vec3 &domega_out_dx, const Vec3 &domega_out_dy, float randu, float randv, Vec3 &omega_in, Vec3 &domega_in_dx, Vec3 &domega_in_dy, float &pdf, Color3 &eval) const { float cosNO = m_N.dot(omega_out); if (cosNO > 0) { // get x,y basis on the surface for anisotropy Vec3 X, Y; make_orthonormals(m_N, m_T, X, Y); // generate random angles for the half vector // eq. 7 (taking care around discontinuities to keep // output angle in the right quadrant) // we take advantage of cos(atan(x)) == 1/sqrt(1+x^2) // and sin(atan(x)) == x/sqrt(1+x^2) float alphaRatio = m_ay / m_ax; float cosPhi, sinPhi; if (randu < 0.25f) { float val = 4 * randu; float tanPhi = alphaRatio * tanf((float) M_PI_2 * val); cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi); sinPhi = tanPhi * cosPhi; } else if (randu < 0.5) { float val = 1 - 4 * (0.5f - randu); float tanPhi = alphaRatio * tanf((float) M_PI_2 * val); // phi = (float) M_PI - phi; cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi); sinPhi = -tanPhi * cosPhi; } else if (randu < 0.75f) { float val = 4 * (randu - 0.5f); float tanPhi = alphaRatio * tanf((float) M_PI_2 * val); //phi = (float) M_PI + phi; cosPhi = -1 / sqrtf(1 + tanPhi * tanPhi); sinPhi = tanPhi * cosPhi; } else { float val = 1 - 4 * (1 - randu); float tanPhi = alphaRatio * tanf((float) M_PI_2 * val); // phi = 2 * (float) M_PI - phi; cosPhi = 1 / sqrtf(1 + tanPhi * tanPhi); sinPhi = -tanPhi * cosPhi; } // eq. 6 // we take advantage of cos(atan(x)) == 1/sqrt(1+x^2) // and sin(atan(x)) == x/sqrt(1+x^2) float thetaDenom = (cosPhi * cosPhi) / (m_ax * m_ax) + (sinPhi * sinPhi) / (m_ay * m_ay); float tanTheta2 = -logf(1 - randv) / thetaDenom; float cosTheta = 1 / sqrtf(1 + tanTheta2); float sinTheta = cosTheta * sqrtf(tanTheta2); Vec3 h; // already normalized becaused expressed from spherical coordinates h.x = sinTheta * cosPhi; h.y = sinTheta * sinPhi; h.z = cosTheta; // compute terms that are easier in local space float dotx = h.x / m_ax; float doty = h.y / m_ay; float dotn = h.z; // transform to world space h = h.x * X + h.y * Y + h.z * m_N; // generate the final sample float oh = h.dot(omega_out); omega_in.x = 2 * oh * h.x - omega_out.x; omega_in.y = 2 * oh * h.y - omega_out.y; omega_in.z = 2 * oh * h.z - omega_out.z; if (Ng.dot(omega_in) > 0) { float cosNI = m_N.dot(omega_in); if (cosNI > 0) { // eq. 9 float exp_arg = (dotx * dotx + doty * doty) / (dotn * dotn); float denom = 4 * (float) M_PI * m_ax * m_ay * oh * dotn * dotn * dotn; pdf = expf(-exp_arg) / denom; // compiler will reuse expressions already computed denom = (4 * (float) M_PI * m_ax * m_ay * sqrtf(cosNO * cosNI)); float power = cosNI * expf(-exp_arg) / denom; eval.setValue(power, power, power); domega_in_dx = (2 * m_N.dot(domega_out_dx)) * m_N - domega_out_dx; domega_in_dy = (2 * m_N.dot(domega_out_dy)) * m_N - domega_out_dy; /* disabled for now - gives texture filtering problems */ #if 0 // Since there is some blur to this reflection, make the // derivatives a bit bigger. In theory this varies with the // roughness but the exact relationship is complex and // requires more ops than are practical. domega_in_dx *= 10; domega_in_dy *= 10; #endif } } } return Labels::REFLECT; } }; ClosureParam bsdf_ward_params[] = { CLOSURE_VECTOR_PARAM(WardClosure, m_N), CLOSURE_VECTOR_PARAM(WardClosure, m_T), CLOSURE_FLOAT_PARAM (WardClosure, m_ax), CLOSURE_FLOAT_PARAM (WardClosure, m_ay), CLOSURE_STRING_KEYPARAM("label"), CLOSURE_FINISH_PARAM(WardClosure) }; CLOSURE_PREPARE(bsdf_ward_prepare, WardClosure) CCL_NAMESPACE_END